Engine and piston

Abstract

An engine includes a cylinder block having a bore, a piston fitted into the bore so as to form a combustion chamber and to be able to reciprocate, a cylinder head for closing the combustion chamber and having valve bores communicating with the combustion chamber, and valves for opening and closing the valve bores. A heat insulating coating is applied on a wall face of at least one of the piston, the cylinder head, and the valves and facing the combustion chamber. The heat insulating coating includes resin and a plurality of hollow nanoparticles embedded in the resin, smaller in diameter than a thickness of the heat insulating coating, and smaller than or equal to 500 nanometers in size.

Description

TECHNICAL FIELD[0001]The present invention relates to an engine and a piston with improved heat insulation of a combustion chamber.BACKGROUND ART[0002]An engine includes a cylinder block having a bore, a piston fitted into the bore so as to form a combustion chamber and to be able to reciprocate, a cylinder head which closes the combustion chamber and has a valve bore communicating with the combustion chamber, and a valve for opening and closing the valve bore. In order to improve fuel efficiency, it is preferable to improve heat insulation of the combustion chamber. Especially in a vehicle, such as a hybrid vehicle and a vehicle having an idling stop function, which is intended to improve the fuel efficiency, driving of the engine may be stopped temporarily during traveling or a brief stop of the vehicle in some cases. In these cases, because a temperature of the combustion chamber in the engine is likely to reduce, there is a limit on the improvement of the fuel efficiency of the ...

AI Technical Summary

Benefits of technology

[0019]According to the invention, employment of the heat insulating coating having high heat insulation and high surface smoothness improves heat insulation of the combustion chamber and contributes to improvement of fuel efficiency of the engine. Furthermore, because the surface smoothness of the top of the piston can be increased, it is possible to suppress knocking of the engine.

[0020]According to the invention, because the heat insulation of the combustion chamber of the engine can be improved as described above, thermal efficiency of the engine at the time of cold start is improved and the fuel efficiency of the engine is improved. In general, at the time of the cold start of the engine, fuel is not vaporized well and therefore a larger amount of fuel (such as gasoline) than usual is sent into the combustion chamber. However, if the heat insulating coating according to the invention is provided, it is possible to effectively carry out heat insulation of the combustion chamber of the engine to thereby improve vaporization of the fuel to improve the fuel efficiency. Especially in hybrid vehicles and idling stop vehicles which are increasing in number in recent years, the engine is not sufficiently warmed up due to intermittent operation of the engine. In this case, the heat insulating coating according to the invention exerts the effect and it is easy to maintain the combustion chamber of the engine at high temperature. Moreover, because combustion heat in the combustion chamber is less liable to escape into the piston, the cylinder block, the cylinder head, and the like, combustion temperature in the combustion chamber increases and an effect on reduction of HC (hydrocarbon) included in exhaust gas can be expected as well.

Problems solved by technology

In these cases, because a temperature of the combustion chamber in the engine is likely to reduce, there is a limit on the improvement of the fuel efficiency of the engine.

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